Document WO 2012/085 446 describes a device forming the workpiece clamp comprising a body having a first face for securing by vacuum to a workbench and a second face for securing by vacuum a workpiece. The body contains a vacuum pump and a rechargeable electric battery for powering said vacuum pump. A buffer reserve of vacuum connected to the vacuum pump ensures even operation of the vacuum pump and prevents repeated closely-spaced stops and starts. A fluid curtain arranged at the periphery of the upper second face forming a suction cup for securing by means of vacuum may be provided in order to form a concentric capillary seal and prevent the upper second face forming a suction cup for securing by vacuum from coming unstuck furthermore preventing the ingress of dust, sludge, undesirable chips or other particles. Filters are provided on the fluid curtain circuit and on the vacuum pump vacuum circuit.
The device of document WO 2012/085 446 is satisfactory when the workpieces are workpieces that have a relatively smooth surface allowing the second face for securing by vacuum to adhere well. However, application of this device to the clamping of workpieces made up of materials that are rocky, abrasive or generate dust, impurities or chips presents a number of disadvantages.
On the one hand, the presence of dust, impurities or chips prevents a good seal between the securing faces and produces leaks of vacuum entailing a repeated running of the vacuum pump.
On the other hand, the plugging or contamination of the protective filters means that frequent cleaning is required and significant pressure drops are created in the flows of air or fluid within the workpiece clamp.
These disadvantages may also lead to the vacuum pump and the fluid curtain supply pump having a limited life.
Finally, the gripping of the workpiece on the upper securing suction cup is sometimes imperfect, and this too leads to sources of leakage and detracts from the good quality of the clamping.